libsodium

It contains a folder builds/msvc/ with all the solutions for recent and old versions of Visual Studio. Pick yours.

Open Project > Properties.

Select All configurations and change the toolset to support target XP.

Select all Debug configurations (either one by one or with the multiple selection tool) and change Target Name so that d is added to the filename base (for instance $(TargetName)d instead of $(TargetName)).

Copy headers to libraries/win32/libsodium/include/. It looks like the build doesn't create a minimal folder of headers, so my advice is downloading the zip with prebuilt libs for msvc from ​the download page and using the include folder from that.